The time interval between vaccinations is generally a time period within which vaccination is recommended. The misconception of 21-day interval vaccination is generally that some people think that the vaccination must be completed on the day after the 21-day interval, but in fact, as long as the vaccination is given within the specified time period, the immunization effect can be achieved. Not all vaccines require a 21-day interval, and the vaccines that currently require a 21-day interval are usually the new crown vaccine. In addition, some people may mistakenly believe that if they do not receive the second or third vaccination within the prescribed time, the first vaccination is ineffective and they may give up completely to continue the rest of the vaccination. In general, the vaccine has some protective effect even if only one dose is given, but the protective effect produced by the vaccine may be lower. Delaying the second dose of the vaccine does not affect the effectiveness of the first dose; the second dose of the vaccine is given to enhance the immune effect of the vaccine. Some people may think that they need to be re-vaccinated after the vaccination period, but this is not necessary and only the remaining vaccine is needed. In the case of inactivated New Coronavirus vaccine, for example, if the second or third dose of the vaccine is not completed at the required time, a delay of a few days will not usually affect the effectiveness of the vaccine and the second or third dose can be continued. However, it is still recommended to follow the vaccination procedures of the specific vaccine and to receive the vaccine within the prescribed time period to achieve better immunization results.